In recent years, headphone devices or earphone devices with a noise cancellation function or head mounted display (HMD) devices have become widespread. For users who use such devices, information from the surroundings is auditorily or visually blocked, and thus a sense of immersion is easily experienced. On the other hand, a user using such a device can enjoy a sense of immersion but is unable to easily understand that surrounding people say.
In this regard, a technique of determining a degree of necessity of notifying a user of external information on the basis of external information indicating an external situation of the user and switching a state of notifying the user of the external information on the basis of the determined degree of necessity is disclosed in Patent Literature 1. According to such a technique, a user wearing a shielding type HMD device can communicate with an outside person more smoothly.